Conventionally, an electric current that flows into a current circuit for rotating a motor increases when a mechanical load becomes heavy in an electric appliance that uses the motor as a power source. Moreover, when the load becomes excessively heavy, rotations of the motor are extremely slowed down or stopped.
When the rotations of the motor are extremely slowed down or stopped as described above, an electric current further increases. As a result, the motor produces heat and shortcircuits or burns out a coil, so that the motor is destroyed.
To protect the motor by preventing such a problem, a protector is used to immediately interrupt a current applied to a driving circuit of the motor by sensing heat or a current when the motor excessively produces heat or the current of the driving circuit of the motor excessively increases.
Such a protector is called diversely, such as a temperature switch, a thermal protector, or the like. For example, a heat protector, which is configured to be suitable for a safety backup of an electric appliance that needs less components and assembly operations and utilizes a heating element of a covered type, uses iron as a cover of a main body of the switch, and takes the shape of a swaged terminal in order to facilitate a connection between the terminal and a lead wire, is proposed (for example, see Patent Document 1).
Additionally, it is essential that the position of a fixed contact, which is one of members that configure a switch unit, is fixed as its name represents and not moved by an external factor such as vibrations or the like. As such an example, a directly connected yoke terminal configured to be fixed to a base by bending a stake arm (fixed arm) integrated with the yoke terminal (fixed contact) as one body when being attached to the base is proposed (for example, see Patent Document 2).
Incidentally, a temperature switch as a motor protector is installed for a winding of a motor, and needs to prevent a temperature of the winding from exceeding a temperature limit due to an overload or an overcurrent. With this installation, the temperature switch is directly attached to the winding in some cases. Accordingly, the temperature switch needs to have an insulative property bearable for such attachment.
In such a case, for the protector having an outer covering of a conductive member shaped like an iron cover as in the protector referred to in Patent Document 1, it is needed to attach a connection part between a terminal and a lead wire to a coil of a motor after the connection part is insulated with an insulation tube or the like. If possible, it is preferable to cover also the outer covering with an insulation member.
Additionally, as referred to in Patent Document 2, it is needed to insulate the entire protector inclusive of a swaged part, a terminal linked to the swaged part, and a lead wire after the terminal is swaged and the lead wire is connected when the lead wire is connected to the terminal.
Consequently, a problem of causing difficulty in fixing the protector to the coil of the motor is posed since the size of the entire protector increases when a large-sized insulation member is added as described above. To solve this problem, the issue of insulation is relieved by configuring the main body of the protector with an insulative resin housing.
Namely, it is sufficient to insulate only the swaged part, and the terminal connected to the swaged part, and the lead wire so that a non-insulative part is not exposed outside the resin housing.